This invention relates to an improvement in a tablet feed mechanism of a tablet feeder for supplying tablets including capsules.
A conventional tablet feeder for supplying tablets to tablet packaging devices is disclosed in unexamined Japanese patent publication 9-323702. The tablet feeder has a rotor rotatably mounted in the bottom of a tablet storage case which is detachably mounted from a horizontal direction with respect to a support base in which is mounted a motor for driving the rotor.
The bottom portion in the storage case is formed into a recess in which is received the rotor of a conical shape so as to be rotatable about its rotation axis. An idler gear is mounted at the bottom end. When the storage case is mounted on the support base, a drive gear at the end of the output shaft of the motor in the support base is adapted to engage the idler gear. The support base is provided with a discharge path for discharging tablets obliquely downwardly. The rotor has along its outer circumference a plurality of pockets into which tablets are dropped. When each pocket aligns with the discharge path, the tablet in the pocket drops and is discharged downwardly.
The tablet feeder is controlled such that tablets in the pockets are dispensed one at a time by rotating the rotor, the dispensed number is counted. When a preset tablet number is reached, the rotor is stopped by stopping the motor. Thus, if the dispensing speed is increased by increasing the speed of the rotor, when the number of tablets has reached the preset number by the sensor detection and the rotor is brought to a sudden stop, the rotor will not necessarily stop precisely at the position where the stop signal has been produced but rotates slightly from this position due to its inertia.
Thus, when the pocket in which is received a tablet following the tablet that has been dispensed last time approaches close to the position of the discharge path and is stopped, although it may not rotate to the position right over the discharge path, it may stop at a position very close to such a position according to the kind of tablets, rotation speed, and various other conditions.
To cope with this problem, the tablet feeder disclosed in the abovesaid publication has at the lower bottom of the tablet storage case a rotation preventive means for preventing rotation of the rotor when the storage case is dismounted, by engaging a drive gear provided on a rotary shaft at the bottom end of the rotor.
However, since the rotation preventive means in the conventional tablet feeder is a means for mechanically preventing rotation of the rotor when the storage case is dismounted from the support base, this means cannot stop the rotor by a stop signal based on tablet detection by a sensor directly at a desired position. Thus, the pocket of the next tablet can stop at a position very close to the discharge path.
Also, the rotation preventive means can merely prevent the rotation of the rotor when the storage case is dismounted. If the engagement of the rotation preventive means is released and the rotor rotates either forwardly or backwardly by a very small distance, e.g. one tooth of the gear when the tablet feeder is replaced with another tablet feeder and the storage case is remounted, the pocket in question may stop at a position very close to the discharge path. The pocket may thus align with it. Thus, tablets may still drop inadvertently.
An object of this invention is to provide a tablet feeder so adapted that the rotor can be stopped at a predetermined position by a stop means having a simple structure when the rotation of the rotor stops, thereby preventing tablets from dropping inadvertently when the storage case is mounted or dismounted.
Another object is to provide a tablet feeder which can prevent the rotor from rotating in a reverse direction, thereby preventing the partitioning member from being damaged.
According to this invention, there is provided in a tablet feeder comprising a tablet storage case having a bottom portion, a rotor rotatably mounted in the bottom portion of the tablet storage case, and a motor for driving the rotor. The rotor is formed with a plurality of pockets for receiving tablets therein, and when each of the pockets aligns with a discharge path provided under the rotor, the tablets can be discharged. Also, a predetermined position stop means is provided for the purpose of stopping the rotor at a predetermined position.
According to this invention, the storage case in which are stored tablets is detachably mounted on the support table, and the tablets are discharged through the discharge path and supplied to e.g. a drug packaging device. This tablet supply action is performed by rotating the rotor and discharging one tablet every time one of the pockets formed in the rotor outer surface aligns with the discharge path. Such tablet supply action itself is the same as with a conventional tablet feeder.
But when the storage case is dismounted or removed from the support table to replenish the tablets in the tablet feeder, if the rotor is at a stop immediately before the position where a tablet will drop into the discharge path, due to slight shift in meshing of rotary gears, the rotor tends to rotate, so that a tablet can drop inadvertently. Such an accident will not happen in the tablet feeder of this invention.
When the rotor is stopped, a stopping force is applied to the rotor by the predetermined position stop means to stop the rotor at a predetermined position. Once the rotor stops, unless a rotational force that is sufficient to rotate the rotor against the stopping force is applied, it will never rotate. Thus, the rotor cannot easily be rotated due to a shift in meshing of rotary gears while the storage case is being dismounted or even if someone attempts to purposely rotate the rotor. Thus, tablets will never drop inadvertently.
Also, if the partitioning member comprising the whisker-like resilient member for partitioning tablets in the pockets is fixed to the bottom portion at a position facing the discharge path, a reverse rotation preventive means is preferably mounted at the bottom end of the rotary shaft of the rotor. This prevents the whisker-like resilient member from being damaged due to reverse rotation of the rotor.